Let
x--------> the time in hours
y-------> the distance in miles
we know that
The speed is equal to

in this problem


<u>Equation First Train</u>

<u>Equation Second Train</u>

---------> equation 
Substitute the values of
and
in the equation 

Solve for x


therefore
<u>the answer is</u>

Step-by-step explanation:
a) The circumference of a circle is 360 degrees. so:
7x+15+8x+6x+30=360
21x+45=315
21x=135
x=<u>15</u>
b) This means 7(15)+15=120, 8(15)=120, and 6(15)+30=120. Thus, by the inscribed angle theorem, all the angles measure 60 degrees, and the triangle is thus <u>equilateral</u> and <u>isosceles</u>.
5(x+2) turns into 5x+10 where 5x+2 is already in its simplified form so to write it as 5x+2 instead would make you get the wrong answer.
2/3-1/4=5/12
You could make the denominators common by finding the GCF
The GCF of 4 and 3 is 12
This means that 8/12-3/12 which would give you 5/12.
:)
Y= 12*x
Y=12x
In short, y is a product of 12 and x